In UBIK®, a MetaClass is used to define the appearance and behavior of a certain set of future content objects or Instances.
A MetaClass can, and actually has to, inherit from another MetaClass, so it is usually also a Derivate. The inherit source can be a built in Metaclass, which is typically the case when customizing starts in an "empty" data model. Of course, and more likely, it will be another MetaClass that was already created during customizing.